Messages in this thread | | | Date | Tue, 15 Jun 2010 11:03:33 -1000 | From | Zachary Amsden <> | Subject | Re: [PATCH 12/17] Add helper function get_kernel_ns |
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On 06/14/2010 10:41 PM, Avi Kivity wrote: > On 06/15/2010 10:34 AM, Zachary Amsden wrote: >> Add a helper function for the multiple places this is used. Note >> that it >> must not be called in preemptible context, as that would mean the kernel >> could enter software suspend state, which would cause non-atomic >> operation >> of the monotonic_to_bootbased computation. >> >> Open question: should the KVM_SET_CLOCK / KVM_GET_CLOCK ioctls use this >> as well? Currently, they are not bootbased (but perhaps should be). >> >> Signed-off-by: Zachary Amsden<zamsden@redhat.com> >> --- >> arch/x86/kvm/x86.c | 26 +++++++++++++------------- >> 1 files changed, 13 insertions(+), 13 deletions(-) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 703ea43..15c7317 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -915,6 +915,16 @@ static void kvm_get_time_scale(uint32_t >> scaled_khz, uint32_t base_khz, >> __func__, base_khz, scaled_khz, shift, *pmultiplier); >> } >> >> +static inline u64 get_kernel_ns(void) >> +{ >> + struct timespec ts; >> + >> + WARN_ON(preemptible()); >> + ktime_get_ts(&ts); >> + monotonic_to_bootbased(&ts); >> + return timespec_to_ns(&ts); >> +} >> + >> static DEFINE_PER_CPU(unsigned long, cpu_tsc_khz); >> > > Isn't something like this a candidate for the time infrastructure? >
Should it be? It certainly seems reasonable.
Also, should we be using it for the cases KVM_GET_CLOCK / KVM_SET_CLOCK? It seems global kvmclock_offset for the VM ignores the bootbased conversion.
Zach
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